(1) Field of the Invention
The present invention relates to a non-sintered nickel electrode for use in an alkaline storage cell such as a nickel-hydrogen storage cell, a nickel-cadmium storage cell. The present invention also relates to an alkaline storage cell utilzing the electrode.
(2) Description of the Prior Art
In impregnating an active material into a substrate, a non-sintered substrate generally makes it possible to achieve a higher impregnating density, in comparison with a sintered substrate. However, when a porosity of the substrate is raised in order to increase the impregnating density, the proportion of the active material being not immediately in contact with the substrate is increased, and therefore the current collection efficiency of the substrate is degraded, inducing the decrease of an active material utilization rate. Thus, even if the impregnating density is increased in impregnating an active material using a substrate with a large porosity, an actual capacity of a cell cannot be sufficiently increased. In view of such a problem, Japanese Unexamined Patent Publication No. 3-147258 discloses such a technique that, for a non-sintered nickel electrode, a plated layer of cobalt is formed on the surface of an active material consisting of nickel hydroxide. According to this technique, since the cobalt layer formed on the surface of nickel hydroxide enhances the conductivity between the active material particles, the active material utilization rate of the electrode is improved, resulting in an increase of a discharge capacity.
However, in course of the rapid development of mobile electronic devices and the like, there is a growing need for a cell having a higher energy density and a longer cycle life. In consideration of such circumstances, there is still an ample room for improvement in the technique described above. In particular, a short cycle life of the cell still lies as a problem.